This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Marfan syndrome is an autosomal dominant connective tissue disorder which includes features such as aortic root dilatation with possible aneurysm and dissection, ocular lens dislocation, scoliosis and long, thin limbs and muscle weakness. We propose an ancillary study to quantify muscle strength, endurance, mass and quality, and bone mineral content and density at baseline and throughout this trial. Muscle strength and endurance will be quantified by a Total Muscle Strength (TMS) Score and body composition will be quantified via anthropometry DEXA. Muscle volume, signal and architecture will be assessed via MRI of the lower extremities.